1 files changed, 85 insertions, 0 deletions
diff --git a/test/text/cross_tile_symbol_index.test.cpp b/test/text/cross_tile_symbol_index.test.cpp
new file mode 100644
index 0000000000..b40827d63e
--- /dev/null
+++ b/test/text/cross_tile_symbol_index.test.cpp
@@ -0,0 +1,85 @@
+#include <mbgl/text/cross_tile_symbol_index.hpp>
+#include <mbgl/renderer/buckets/symbol_bucket.hpp>
+#include <mbgl/test/util.hpp>
+
+using namespace mbgl;
+
+SymbolInstance makeSymbolInstance(float x, float y, std::u16string key) {
+    GeometryCoordinates line;
+    GlyphPositionMap gpm;
+    const std::pair<Shaping, Shaping> shaping(Shaping{}, Shaping{});
+    style::SymbolLayoutProperties::Evaluated layout_;
+    IndexedSubfeature subfeature(0, "", "", 0);
+    Anchor anchor(x, y, 0, 0);
+    return {anchor, line, shaping, {}, layout_, 0, 0, 0, 0, style::SymbolPlacementType::Point, {{0, 0}}, 0, 0, {{0, 0}}, gpm, subfeature, 0, key, 0 };
+}
+
+
+TEST(CrossTileSymbolLayerIndex, addBucket) {
+
+    uint32_t maxCrossTileID = 0;
+    CrossTileSymbolLayerIndex index;
+
+    style::SymbolLayoutProperties::PossiblyEvaluated layout;
+    bool sdfIcons = false;
+    bool iconsNeedLinear = false;
+    bool sortFeaturesByY = false;
+
+
+    OverscaledTileID mainID(6, 0, 6, 8, 8);
+    std::vector<SymbolInstance> mainInstances;
+    mainInstances.push_back(makeSymbolInstance(1000, 1000, u"Detroit"));
+    mainInstances.push_back(makeSymbolInstance(2000, 2000, u"Toronto"));
+    SymbolBucket mainBucket { layout, {}, 16.0f, 1.0f, 0, sdfIcons, iconsNeedLinear, sortFeaturesByY, std::move(mainInstances) };
+    index.addBucket(mainID, mainBucket, maxCrossTileID);
+
+    // Assigned new IDs
+    ASSERT_EQ(mainBucket.symbolInstances.at(0).crossTileID, 1u);
+    ASSERT_EQ(mainBucket.symbolInstances.at(1).crossTileID, 2u);
+
+
+    OverscaledTileID childID(7, 0, 7, 16, 16);
+    std::vector<SymbolInstance> childInstances;
+    childInstances.push_back(makeSymbolInstance(2000, 2000, u"Detroit"));
+    childInstances.push_back(makeSymbolInstance(2000, 2000, u"Windsor"));
+    childInstances.push_back(makeSymbolInstance(3000, 3000, u"Toronto"));
+    childInstances.push_back(makeSymbolInstance(4001, 4001, u"Toronto"));
+    SymbolBucket childBucket { layout, {}, 16.0f, 1.0f, 0, sdfIcons, iconsNeedLinear, sortFeaturesByY, std::move(childInstances) };
+    index.addBucket(childID, childBucket, maxCrossTileID);
+
+    // matched parent tile
+    ASSERT_EQ(childBucket.symbolInstances.at(0).crossTileID, 1u);
+    // does not match because of different key
+    ASSERT_EQ(childBucket.symbolInstances.at(1).crossTileID, 3u);
+    // does not match because of different location
+    ASSERT_EQ(childBucket.symbolInstances.at(2).crossTileID, 4u);
+    // matches with a slightly different location
+    ASSERT_EQ(childBucket.symbolInstances.at(3).crossTileID, 2u);
+
+    OverscaledTileID parentID(5, 0, 5, 4, 4);
+    std::vector<SymbolInstance> parentInstances;
+    parentInstances.push_back(makeSymbolInstance(500, 500, u"Detroit"));
+    SymbolBucket parentBucket { layout, {}, 16.0f, 1.0f, 0, sdfIcons, iconsNeedLinear, sortFeaturesByY, std::move(parentInstances) };
+    index.addBucket(parentID, parentBucket, maxCrossTileID);
+
+    // matched child tile
+    ASSERT_EQ(parentBucket.symbolInstances.at(0).crossTileID, 1u);
+
+    std::unordered_set<uint32_t> currentIDs;
+    currentIDs.insert(mainBucket.bucketInstanceId);
+    index.removeStaleBuckets(currentIDs);
+
+    // grandchild
+    OverscaledTileID grandchildID(8, 0, 8, 32, 32);
+    std::vector<SymbolInstance> grandchildInstances;
+    grandchildInstances.push_back(makeSymbolInstance(4000, 4000, u"Detroit"));
+    grandchildInstances.push_back(makeSymbolInstance(4000, 4000, u"Windsor"));
+    SymbolBucket grandchildBucket { layout, {}, 16.0f, 1.0f, 0, sdfIcons, iconsNeedLinear, sortFeaturesByY, std::move(grandchildInstances) };
+    index.addBucket(grandchildID, grandchildBucket, maxCrossTileID);
+
+    // Matches the symbol in `mainBucket`
+    ASSERT_EQ(grandchildBucket.symbolInstances.at(0).crossTileID, 1u);
+    // Does not match the previous value for Windsor because that tile was removed
+    ASSERT_EQ(grandchildBucket.symbolInstances.at(1).crossTileID, 5u);
+
+}